Wednesday, June 19, 2013

Nikon D7000 vs. Nikon D7100

D7000 + Tokina 11-16

I've been using the Nikon D7000 for a couple of months now, and in this post I'd like to share my thoughts on the Nikon D7000 and Nikon D7100, after having about 1600 shots on each.


BACKGROUND
I got the Nikon D7100 on launch day and was very pleased with it.  Here is my review.  However, I found that it was susceptible to banding if I make significant exposure adjustments during postprocessing.  Because I often do just that for scenes with a wide dynamic range, I returned the D7100.  Only later on did I find that the banding could actually be significantly mitigated using RawTherapee.

Meanwhile, however, I got a D7000 as a replacement.  I chose the D7000 because the cost had dropped significantly and partly because I could use it with an external tilting LCD, the Aputure Gigtube (reviewed here).

In this post, I'd like to discuss the most significant differences I've found between these two cameras.  My concern is not so much on theoretical differences between them, but whether their differences matter to me the way I normally use my cameras.  

At the time I got the D7100, I upgraded from the 12-megapixel D300S (and before that the D90).  The D7100 was therefore a major upgrade for me in many ways, not the least of which was the resolution.  However, I usually don't make large prints and 95% of the time, I post my shots for online viewing only, at web sizes.  In my case web size means 1200 or 1600 pix, and I view them on a mere 15 inch laptop screen.

SHARPNESS

When I first got the D7100, I was surprised that the D7100 shots did look sharper to me, even at moderate web resolutions (1200 or 1600 pixels on the long edge).  The D7100 web-sized shots had a certain crispness to them that I had not seen from any of my previous DX cameras.  You can click on the images below for 1600-pix versions.

D7100 with 28-105 3.5-4.5D at f/4.2
D90 with 24-70 2.8G at f/4
On the other hand, between the D7100 and D7000, the difference in resolution is not as great.  Below are test shots I was able to take the day I got the D7100 (please ignore the filenames and EXIF) with the same 35 1.8G lens.  Please note that on the D7100 shot, I adjusted the exposure +1/3 stop to account for the difference in real ISO between the two cameras (as found by DPReview).  When I compare the test shots below at this web-size resolution (1600 pix), I can't see a difference.

D7000

D7100

Here are a couple of real-world web-size samples (at 1200 pix).  In both shots, I used the Tokina 11-16 at f/2.8, although the exposures are different, and there is a difference in focusing distance (and hence DoF).

D7000 + Tokina 11-16 @ f/2.8, 1/2000, ISO 100.

D7100 + Tokina 11-16 @ f/2.8, 1/100, ISO 250.
NOISE
One of the strengths of the Nikon D7100 is its low noise.  Actually when D7100 shots are viewed 100% they are about the same as that of the D7000.  However, when a 24mp D7100 shot is viewed at the same size as a 12mp photo from the Nikon D3 or D700, they appear to have about the same amount of noise (IOW, the D7100 is just as good in terms of noise as the D700 even though the latter is full frame).  Resizing a D7100 image to match the 16mp D7000 size also has a similar effect of making noise less apparent, but the effect is more noticeable at higher ISOs.  See this post for more information.

The issue is, would the D7100 still have better noise than the D7000 at the sizes I usually view my shots?  Check out the test shots above at the camera store.  Both were at ISO 6400 with no noise reduction applied, and to me, they are both clean enough at these smaller viewing sizes.

Here are two real world samples at still higher ISOs.  The light conditions in them are not the same because to be honest I have very few shots at extremely high ISOs and these were the only ones I saw that were somewhat comparable.  The D7100 shot is at ISO 12800, with no flash.  The D7000 shot was at ISO 3200 but pushed two stops, also with no flash.  You can click on them for 1200-pix versions.
D7100, ISO 12800

D7000, D3200 + 2 stops (~ 12800). Note: image intentionally desaturated
The D7100 shot is of course sharper because the subject is not moving.  With respect to noise, the D7100 looks a little cleaner to me, though the difference is not so obvious at smaller viewing sizes.

BANDING
As I mentioned above, I was very concerned with the D7100's banding because I do push my exposure from time-to-time for high contrast scenes, such as this:


D7000 + Tokina 11-16.  After postprocessing.
Straight out of the camera.

In the shot above, I intentionally underexposed to preserve the detail in the sky outside. In Lightroom, I had to push the exposure +4.68 EV and +34 shadow to get the final shot.  With the D7000 there is no banding even at these extreme adjustments.  With the D7100, banding would have appeared with these extreme adjustments.

However, viewing the images at web sizes, the D7100 banding is not visible.  Here is a shot that does have banding (in this version of this shot, I did not use RawTherapee):
D7100-1711-201303311215.jpg

At web sizes, the banding is not visible, even at a 2048-pix size.  This means that it only becomes necessary to mitigate banding when you need to make very large prints (or when you want to engage in internet debates).  BTW, you can click on the shot to see other resolutions, including the full 24mp resolution where banding is visible.

AUTOFOCUS
I liked the autofocus of the D7100, not just because its 51 AF points covered most of the frame, but because it was snappy and worked well in low light.  I have never experienced the D7100 autofocus hesitating in low light, even when I shot in very dark conditions.

On the D7000, the 39 AF points are adequate for me.  They encompass the intersections of the rule of thirds.  There are occasions when the extra coverage of the 51 AF points would have been useful but I can make do with the 39 AF points.

As for low light, I did encounter situations where the D7000 has sometimes found it difficult to autofocus in low light, especially with slower lenses.  On the whole, however, I found the D7000 autofocus performance to be adequate.

I have heard some people complain about the D7000's autofocus accuracy, but I haven't had any issues with accuracy (I do use AF fine tuning for my lenses).

AUTO ISO
One of my favorite features on the D7100 is its smarter Auto ISO.  Like the D600, the D7100 can take the focal length into account for the minimum shutter speed.  Moreover, the D7100 uses the effective focal length with the 1.5x crop factor.

That is one of the features I miss on the D7000.  With the D7000, I just have to set the minimum shutter speed manually (usually around 1/125).  Activating Auto ISO is also not as easy on the D7000.  On the D7100, I could hold the ISO button and the sub-command dial to activate it.  On the D7000, there is no such option.  Instead, I assign Auto ISO to the top item in My Menu and use the Fn button to activate the top item in My Menu, i.e. Auto ISO.

IMAGE REVIEW
When reviewing images on the D7100, you can set the OK button to show a 100% view of the image to quickly confirm autofocus accuracy.  The D7000 has no such feature (neither does the D600).

EFFECT OF EXPOSURE COMPENSATION ON FLASH

Historically, on Nikon cameras, adjusting exposure compensation will affect both the ambient exposure and flash exposure (whereas on Canon cameras, adjusting exposure compensation only affects ambient exposure). For example, if you want to underexpose the background while having a subject lit by flash with normal exposure, then you would dial -2 exposure compensation let's say (to underexpose the background), but because the -2 exposure compensation also affects flash exposure, you need to raise the flash exposure by +2 to offset the reduction. Regardless of Nikon's reasons for its implementation, I don't like it and it slows me down.

The Nikon D4 was the first Nikon camera to include an option to change the effect of exposure compensation. You could specify whether exposure compensation affects both ambient and flash or just ambient. Although this new feature was not included in the D800, it did make its way to the D600 (one of the reasons I really like the D600), and it also was included in the D7100. To me, this is a significant advantage of the D7100 over the D7000, if you often use TTL flash with semi-automatic exposure (Program, Aperture priority, or Shutter priority).


LIVE VIEW
The implementation of live view on the D7100 is the same as that of the D600: both of them have a live view button, surrounded by a switch between photo and movie mode.  To toggle live view, you press the live view button.

The live view control on the D7000 is different.  There is a button surrounded by a switch but they have different functions from those of the D7100 and D600.  To activate Live view, you flick the spring-mounted switch.  There are no separate photo or movie modes.  Instead, when live view photo is active, it behaves like live view photo mode.  To record a movie, you press the record button in the middle of the switch.

The D7100 implementation has practical advantages over the D7000 implementation:
1. It is faster to toggle live view by pressing a button than flicking a switch.  This is useful for example when changing the aperture.  I double-tap the button to quickly exit and reenter live view to see the actual aperture in live view.
2. The D7100 has separate Fn and Preview functions for movie mode.  The D7000's Fn and Preview buttons don't change whether you are taking photos or recording a video.
3. The D7100 implementation is less confusing with respect to changing the aperture.  Both the D7000 and D7100 do not allow changing the aperture in real time while live view is active (unless you use a lens with an aperture ring).   In the case of the D7100, when you are in movie mode, rotating the front dial will not change the aperture.  In photo mode, rotating the front dial will change the aperture (even though the change in DOF will not shown in real time in live view) because the photo you take will be taken at the aperture you selected.

In the case of the D7000, rotating the front dial will seem to display a change in aperture.  When taking a photo, indeed, the photo is taken at the aperture you selected.  However, if you record a movie, the movie will be recorded at the aperture you selected at the moment you activated live view.  Rotating the front dial has no effect notwithstanding the change in indicated aperture.

CONCLUSION
The D7100 is the best DX camera I've owned.  It is far better than my previous DX cameras (D70, D80, D90, D300, D300S, even Fuji S5).  However, the D7000 is also better than those cameras and is a reasonable alternative to the D7100.  To me, the most significant advantages of the D7100 over the D7000 are its features: autofocus performance, Auto ISO, instant zoom when reviewing images, more logical flash control, and live view.  With respect to image quality, it depends on how you view your images.  If you make large prints, the D7100 will have better image quality than the D7000.  If, like me, you only view your images online at web viewing sizes, the difference in image quality between the two will not be discernible.  This is true not just for sharpness and noise, but also with respect to banding.

SAMPLES FROM THE D7000
Sigma 35 1.4

Sigma 35 1.4

Sigma 35 1.4

Tokina 11-16
Tokina 11-16

Tokina 11-16

Tokina 11-16

Tokina 11-16